Low profile connectors

ABSTRACT

Modular devices, assemblies, and methods for coupling one or more fixation elements, such as bone fasteners and/or elongate rods. The device includes at least one coupling element having a body portion for receiving a bone fastener and an extension portion extending transversely from the body portion. A locking assembly is received in the coupling element and includes a locking member, a clamp portion, and a ring portion, wherein the locking member is configured to contact an upper portion of the clamp portion and the ring portion is configured to at least partially surround a lower portion of the clamp portion. When unlocked, the bone fastener is moveable within the clamp portion to allow for polyaxial movement of bone fastener relative to the coupling element, and when locked, the bone fastener is fixed relative to the coupling element.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. application Ser. No.14/882,512, filed Oct. 14, 2015, which is a continuation-in-part of U.S.application Ser. No. 14/725,406, filed May 29, 2015, which is acontinuation of U.S. application Ser. No. 13/669,527, filed Nov. 6,2012, now U.S. Pat. No. 9,072,547, which are hereby incorporated byreference in their entireties for all purposes.

FIELD OF THE INVENTION

The invention relates to connectors for fixation elements, includinginterconnecting at least two spinal fixation rods or interconnecting atleast two adjacent vertebrae.

BACKGROUND OF THE INVENTION

Bones and bony structures are susceptible to a variety of weaknessesthat can affect their ability to provide support and structure.Weaknesses and deformities in bony structures have numerous potentialcauses, including degenerative diseases, tumors, fractures, anddislocations. Advances in medicine and engineering have provided healthcare practitioners with a number of devices and techniques foralleviating or curing those weaknesses.

With respect to the spinal column, additional support may be necessaryto address such weaknesses and deformities. Surgical techniques forstabilizing the spinal column, such as spinal fusion, have beendeveloped to eliminate pain and other detrimental effects associatedwith spinal column defects. The placement of one or more screws, rods,plates, or cages may be required in association with some spinalstabilization techniques.

The strength and stability of a dual rod, plate, or other elongatemember assembly can be increased by coupling the two rods with a crossconnector which extends substantially horizontal to the longitudinalaxes of the rods across the spine. Due to a wide variety of factors, thetwo rods are rarely geometrically aligned in clinical situations. Across connector with at least some adjustability can be provided toaccommodate for variations from geometrical alignment.

SUMMARY OF THE INVENTION

The invention relates to devices for coupling first and second elongatespinal fixation elements and for coupling first and second vertebrae.According to one embodiment, the device includes a first connectormember having proximal and distal portions, the distal portion includingan engagement portion configured and dimensioned to provisionallyreceive the first elongate spinal fixation element with an interferencefit; a translation member having proximal and distal portions theproximal portion of the first connector member operatively associatedwith the proximal portion of the translation member to provide polyaxialmovement of the first connector member relative to the translationmember; a second connector member having proximal and distal portions,the distal portion configured and dimensioned to receive the secondelongate spinal fixation element and the proximal portion coupled to thetranslation member; and a first locking member to secure the firstelongate spinal fixation element in the engagement portion of the firstconnector member and to lock the polyaxial movement, fixing the firstconnector member relative to the first translation member.

In additional embodiments in accordance with the disclosure, theproximal portion of the first connector member includes a sphere and thedistal portion of the translation member includes a bore for receivingthe sphere to provide the polyaxial movement. A surface of the bore anda surface of the sphere may further include grooves and the other of thesurface of the bore and the surface of the sphere includes ridges.

Another embodiment of the device features the engagement portion of thefirst connector including proximal and distal arms, at least one of theproximal and distal arms resiliently flexing open to accept the firstelongate spinal fixation element and flexing back to provisionallyreceive the first elongate spinal fixation element with the interferencefit. The first connector member may also include a slit extendingbetween the proximal portion of the first connector member to the distalportion of the first connector member, the slit allowing the resilientflexing of the at least one of the proximal and distal arms of theengagement portion of the first connector. The first locking member mayadditionally include a first set screw and a hole on the first connectormember and operatively associated with the slit such that threading ofthe first set screw into the hole moves the proximal and distal armsrelative to one another to secure the first elongate spinal fixationelement in the engagement portion of the first connector member.Furthermore, the slit may divide the sphere into first and secondportions and wherein threading of the first set screw into the holesplays the first and second portions of the sphere to lock the polyaxialmovement, fixing the first connector member relative to the translationmember. The translation member may additionally include first and secondtranslation elements, the first translation element including theproximal portion of the translation member and the second translationelement including the distal portion of the translation member; andwherein the first and second translation elements are moveablerelatively to each other to adjust a distance between the first andsecond connector members. In some embodiments the first and secondtranslation elements move relative to each other with translationmovement, substantially free of rotation. The first and secondtranslation elements may be coupled with a dove-tail connection. Thefirst and second translation elements may further move relative to eachother along an arced path.

In another embodiment in accordance with the disclosure, a device forcoupling first and second elongate spinal fixation elements includes afirst connector member having proximal and distal portions, the distalportion including an engagement portion configured and dimensioned toprovisionally receive the first elongate spinal fixation element with aninterference fit; a second connector member having proximal and distalportions, the distal portion including an engagement portion configuredand dimensioned to provisionally receive the second elongate spinalfixation element with an interference fit; a translation member havingfirst and second portions, the proximal portion of the first connectormember operatively associated with the first portion of the translationmember to provide polyaxial movement of the first connector memberrelative to the translation member, the proximal portion of the secondconnector member operatively associated with the second portion of thetranslation member to provide polyaxial movement of the second connectormember relative to the translation member; a first locking member tosecure the first elongate spinal fixation element in the engagementportion of the first connector member and to lock the polyaxialmovement, fixing the first connector member relative to the firsttranslation member; and a second locking member to secure the secondelongate spinal fixation element in the engagement portion of the secondconnector member and to lock the polyaxial movement, fixing the firstconnector member relative to the first translation member.

In embodiments of the device including first and second connectors, theproximal portions of the first and second connector members may includea sphere and the proximal and distal portions of the translation memberinclude a bore for receiving the sphere to provide the respectivepolyaxial movement. The engagement portions of the first and secondconnectors may further include proximal and distal arms, at least one ofthe proximal and distal arms resiliently flexing open to accept therespective first or second elongate spinal fixation element and flexingback to provisionally receive the respective first or second elongatespinal fixation element with the interference fit. Additionally, thefirst and second connector members may include a slit extending betweenthe proximal portion of the first connector member to the distal portionof the first connector member, the slit allowing the resilient flexingof the at least one of the proximal and distal arms of the engagementportion of the first and second connectors. The first and second lockingmembers may additionally include a set screw and a hole on therespective first or second connector member and operatively associatedwith the slit such that threading of the set screw into the hole movesthe proximal and distal arms relative to one another to secure therespective first or second elongate spinal fixation element in theengagement portion of the respective first or second connector member.

Further provided for, in accordance with the disclosure, is a method forinterconnecting first and second elongate spinal fixation elements, themethod including: provisionally fitting the first elongate spinalfixation element into an engagement portion of a first connector with aninterference fit, the first connector operatively associated with atranslation member to provide polyaxial movement of the first connectormember relative to the translation member; attaching the second elongatespinal fixation element to a second connector, the second connectorcoupled to the translation member; and locking a locking member providedon the first connector thereby securing the first elongate spinalfixation element in the engagement portion of the first connector memberand locking the polyaxial movement in order to fix the first connectormember relative to the first translation member. In some embodiments ofthe device, the locking member includes a first set screw and a hole onthe first connector member, and the locking step of the method forinterconnecting first and second elongate spinal fixation elementsfurther includes threading the first set screw thereby simultaneouslysecuring the first elongate spinal fixation element and locking thepolyaxial movement. It is further contemplated within the disclosurethat the interconnecting step of the method may be performed within aposterior spinal fusion construct.

In another embodiment, a device for coupling first and second vertebraeincludes a first coupling element and a second coupling element. Thefirst coupling element has a first body portion for receiving a firstbone fastener and an elongate rod portion extending transversely fromthe first body portion. The second coupling element has a second bodyportion for receiving a second bone fastener and an extension portionextending transversely from the second body portion. The extensionportion defines a recess sized and configured to receive the rod portionof the first coupling element. When unlocked, the rod portion ismoveable in the recess to allow for rotational and translationalmovement of the first and second coupling elements. When locked, therelative position of the first and second coupling elements is fixed.

In yet another embodiment, a coupling assembly for securing first andsecond vertebrae includes first and second bone fasteners and first andsecond coupling elements. The first bone fastener has a head and a shaftextending therefrom. The shaft of the first bone fastener is configuredto engage the first vertebra. The second bone fastener has a head and ashaft extending therefrom. The shaft of the second bone fastener isconfigured to engage the second vertebra. The first coupling element hasa first body portion housing a first locking assembly and an elongaterod portion extending transversely from the first body portion. Thefirst locking assembly includes a rotatable locking member, a clampportion, and a ring portion configured to at least partially surround aportion of the locking member and the clamp portion. The head of thefirst bone fastener is received in the clamp portion of the firstlocking assembly. The second coupling element has a second body portionhousing a second locking assembly and an extension portion extendingtransversely from the second body portion. The extension portion definesa recess for receiving the rod portion of the first coupling element.The second locking assembly includes a rotatable locking member, a clampportion, and a ring portion configured to at least partially surround aportion of the locking member and the clamp portion. The head of thesecond bone fastener is received in the clamp portion of the secondlocking assembly. When unlocked, the rod portion is moveable in therecess to allow for rotational and translational movement of the firstand second coupling elements, and when locked, the relative position ofthe first and second coupling elements is fixed.

In another embodiment, a method for affixing a coupling device toadjacent vertebrae includes securing a first bone fastener to a pedicleof a first vertebra; securing a second bone fastener to a pedicle of asecond vertebra; attaching a coupling device to the first and secondbone fasteners; moving the rod portion relative to the extension portionto allow for rotational and translational movement of the first andsecond coupling elements; and locking the position of the rod portion inthe recess to fix the first coupling element relative to the secondcoupling element.

In yet another embodiment, a coupling device includes a coupling elementhaving a body portion for receiving a bone fastener and an extensionportion extending transversely from the body portion; and a lockingassembly received in the coupling element, the locking assemblyincluding a locking member, a clamp portion, and a ring portion, whereinthe locking member is configured to contact an upper portion of theclamp portion and the ring portion is configured to at least partiallysurround a lower portion of the clamp portion. When unlocked, the bonefastener is moveable within the clamp portion to allow for polyaxialmovement of bone fastener relative to the coupling element, and whenlocked, the bone fastener is fixed relative to the coupling element.

In a further embodiment, a coupling assembly includes a first bonefastener having a head and a shaft extending therefrom, the shaftconfigured to engage the first vertebra; a first coupling element havinga first body portion housing a first locking assembly and an extensionportion extending transversely from the first body portion, the firstlocking assembly comprising a rotatable locking member, a clamp portion,and a ring portion configured to at least partially surround a portionof the clamp portion, and the head of the first bone fastener isreceived in the clamp portion. When unlocked, the first bone fastener ismoveable in the clamp portion to allow for polyaxial movement of thebone fastener relative to the first coupling element, and when locked,the position of the bone fastener is fixed relative to the firstcoupling element.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1 is a side view of an embodiment of the cross connector device inaccordance with the disclosure;

FIG. 2 is a side view of a second embodiment of a cross connectordevice;

FIG. 3 is a perspective view of the connector member of the device ofFIG. 1;

FIG. 4 is a cross-sectional view of the connector member of FIG. 3;

FIG. 5 is a cross-sectional view of the translation member of the deviceof FIG. 1 illustrating a dove-tail connection;

FIG. 6 is a perspective view of the translation member of the device ofFIG. 1;

FIG. 7A is a side view of the an open offset connector member inaccordance with the disclosure;

FIG. 7B is a cross-sectional view of the open offset connector member ofFIG. 7A;

FIG. 7C is an exploded view of the locking assembly of the open offsetconnector member of FIG. 7A;

FIG. 7D is an assembled view of the locking assembly of the open offsetconnector member of FIG. 7A;

FIG. 8A is a side view of a closed offset connector member in accordancewith the disclosure;

FIG. 8B is a cross-sectional view of the closed offset connector memberof FIG. 8A;

FIG. 8C is an exploded view of the locking assembly of the closed offsetconnector member of FIG. 8A;

FIG. 8D is an assembled view of the locking assembly of the closedoffset connector member of FIG. 8A;

FIG. 9A is a side perspective view of a side-loading tulip element inaccordance with the disclosure;

FIG. 9B is a cross-sectional view of the side-loading tulip element ofFIG. 9A;

FIG. 9C is an exploded view of the locking assembly of the side-loadingtulip element of FIG. 9A;

FIG. 9D is an assembled view of the locking assembly of the side-loadingtulip element of FIG. 9A;

FIG. 10A is a side perspective view of a closed head tulip element inaccordance with the disclosure;

FIG. 10B is a cross-sectional view of the closed-head tulip element ofFIG. 10A;

FIG. 11A is a side perspective view of a headed rod member in accordancewith the disclosure;

FIG. 11B is a cross-sectional view of the headed rod member of FIG. 11A;

FIG. 11C is an exploded view of the locking assembly of the headed rodmember of FIG. 11A;

FIG. 11D is an assembled view of the locking assembly of the headed rodmember of FIG. 11A;

FIG. 12A is a side perspective view of a one-level connector inaccordance with the disclosure;

FIG. 12B is a cross-sectional view of the one level connector of FIG.11A;

FIG. 12C is an exploded view of the locking assembly of the one levelconnector of FIG. 12A;

FIG. 12D is an assembled view of the locking assembly of the one levelconnector of FIG. 12A;

FIG. 13A is a top view of a fixation plate in accordance with thedisclosure;

FIG. 13B is a side view of the fixation plate of FIG. 13A;

FIG. 14A is a cross-sectional view of an embodiment of a one-levelconnector device;

FIG. 14B is an exploded cross-sectional view of a pedicle-based assemblyincluding the connector device of FIG. 14A;

FIG. 15A is a side perspective view of a headed rod member in accordancewith another embodiment;

FIG. 15B is a cross-sectional view of the headed rod member of FIG. 15A;

FIG. 15C is an exploded view of a headed rod member according to anotherembodiment;

FIG. 16A is a side view of the an open offset connector member inaccordance with another embodiment;

FIG. 16B is a cross-sectional view of the open offset connector memberof FIG. 16A;

FIG. 17A is a side view of a closed offset connector member inaccordance with another embodiment;

FIG. 17B is a cross-sectional view of the closed offset connector memberof FIG. 17A;

FIG. 17C is an exploded view of the closed offset connector member ofFIG. 17A with a bone fastener and elongate bone fixation element;

FIG. 18A is a side perspective view of a one-level connector inaccordance with another embodiment; and

FIG. 18B is a cross-sectional view of the one level connector of FIG.18A.

DETAILED DESCRIPTION OF THE INVENTION

As required, detailed embodiments are disclosed herein; however, it isto be understood that the disclosed embodiments are merely examples andthat the systems and methods described below can be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present subject matter in virtually anyappropriately detailed structure and function. Further, the terms andphrases used herein are not intended to be limiting, but rather, toprovide an understandable description of the concepts.

The terms “a” or “an”, as used herein, are defined as one or more thanone. The term plurality, as used herein, is defined as two or more thantwo. The term another, as used herein, is defined as at least a secondor more. The terms “including” and “having,” as used herein, are definedas comprising (i.e., open language).

Referring now to FIG. 1, a device 100 of the disclosure is illustratedprior to receiving first and second spinal fixation elements (notillustrated). Device 100 includes first and second connector members200A, 200B designed to receive a fixation element, and a translationmember 300 cross-connecting or transconnecting first connector member200A with second connector member 200B. In the embodiment illustrated,first connector member 200A is substantially similar to second connectormember 200B, and connector members 200A, 200B are associated withopposing ends of translation member 300. Although it is advantageous tohave dual connector members 200A, 200B, it should be understood that thedisclosure contemplates a single connector member 200A for receiving thefirst fixation element while another connector, such as the alternativeconnectors disclosed herein or other connectors known or to bedeveloped, connected to translation member 300 for receiving the secondfixation element. Accordingly, the disclosure contemplates device 100including any combination of connector members 200.

The spinal fixation elements to be received may include rods, plates, orother elongate members to be utilized in a spinal fixation construct,such as a posterior fusion procedure, although a variety of known or tobe developed spinal fixation elements are contemplated within thedisclosure. A variety of elongate member sizes are contemplated,according to the construct or situation of the surgical procedure to beperformed. Examples of rod or member sizes contemplated include, but arenot limited to, diameters of 4.75 mm, 5.5 mm, 6.35 mm, and other rods ormembers of similar sizes known or to be discovered for use in spinalfixation procedures.

Additionally referring to FIGS. 3 and 4, connector members 200A, 200Bhave a proximal portion 202, generally referring to the portion ofconnector member 200A, 200B in proximity to the translation member 300,and a distal portion 204, generally referring to the portion of theconnector member 200A, 200B opposite from translation member 300. Anengagement portion 206 is provided on distal portion 204 for receiving afixation element. Proximal portion 202 is operatively associated withtranslation member 300 to permit polyaxial movement, includingrotational movement, of connector member 200A, 200B with respect totranslation member 300. Additionally provided on connector member 200A,200B is a locking member 210, illustrated in FIGS. 3 and 4 as a setscrew, operative to secure a received fixation element in engagementportion 206 while also fixing movement of connector member 200A, 200Bwith respect to translation member 300, i.e. locking the polyaxialmovement.

Locking member 210, as illustrated in the embodiment of FIGS. 3 and 4,includes a locking screw 212 received in a threaded hole or bore 214provided on connector member 200A, 200B. As a result of a threading orrotating, from an applied torsional force on a tool receiving uppersurface of screw 212, of locking screw 212 within hole 214, screw 212advances into hole 214 and into or towards a gap or slit 220 whichextends between distal and proximal portion 202, 204. Accordingly, bydisplacing screw 212 into gap 220, the gap is splayed at both the distaland proximal portions 202, 204, resulting in simultaneously securing afixation element received within engagement portion 206 as well asfixing or locking the polyaxial and rotational movement of the connectormember 200A, 200B with respect to translation member 300. The splayingmay be assisted by a gap wedge 222 positioned between hole 214 and gap220 so as to exert a splaying force on gap 220 as screw 212 advancesinto hole 214 and presses against wedge 222.

An elongate fixation member is provisionally securable in engagementportion 206 through a snap-fit or an interference connection. Engagementportion 206 includes proximal and distal arms 208A, 208B for receivingan elongate fixation member. As an elongate fixation member isintroduced into engagement portion 206, at least one of arms 208A, 208Bresiliently flex open to accept the elongate fixation element and flexback to provisionally receive the fixation element with an interferencefit. The interference fit may be tightened, securing the received spinalfixation element, by splaying the distal portion of gap 220. Thesplaying or separating of the distal portion of gap 220 widens the gapthereby moving arms 208A, 208B with respect to one another resulting ina clamping motion on a received fixation member.

Extending into a bore 310 of translation member 300 is a sphere 230 forproviding polyaxial movement of connection member 200A, 200B withrespect to translation member 300. The polyaxial movement isadvantageous in aiding a surgeon, or other technician, installing thedevice to move, rotate, or adjust device 100 to connect second connectormember 200B with the second elongate member while the first elongatemember is provisionally received within engagement portion 206 of firstconnector member 200A. Once the second elongate member is connected toor secured within second connector member 200B, the polyaxial movementof first connector 200A may be fixed by locking sphere 230 within bore310. In an embodiment of the disclosure, sphere 230 is composed of upperand lower surfaces 232, 234, separated by the proximal portion of gap220. Locking of sphere 230 within bore 310 may accordingly occur bysplaying upper and lower surfaces 232, 234 thereby forcing surfaces 232,234 against an inner wall or surface 312 of bore 310 in order tofrictionally secure sphere 230 from moving or rotating within bore 310.In some embodiments, sphere 230 will advantageously include grooves orridges 236 provided on surfaces 232, 234 and mateable with correspondinggrooves or ridges 314 provided on inner surface 312.

Splaying of both the distal and proximal portions of gap 220advantageously result from turning or rotating locking screw 212. Asscrew 212 is rotated, distal and proximal portions of gap 220 are bothsplayed thereby securing the received elongate fixation member inengagement portion 206 as well as thereby fixing connector member 200A,200B from polyaxial movement with respect to translation member 300.This dual locking mechanism is advantageous for quickly and efficientlysecuring device 100 during a surgical procedure.

In reference now to FIGS. 5 and 6, an embodiment of translation member300 includes first and second translation elements 320, 330. Firsttranslation element 320 is connectable with first connector member 200Aand second translation element 330 is connectable with second connectormember 200B. First and second translation elements 320, 330 are movableor slidable relative to one another to adjust a distance between firstand second connector members 200A, 200B. This translation movementadjusting the distance between first and second connector members 200A,200B along with polyaxial movement of connector members 200A, 200B withrespect to translation member 300, provides for interconnecting firstand second fixation elements. In one embodiment, first and secondtranslation elements 320, 330 move relative to one another along anarced path. In FIG. 2, an additional embodiment is illustrated depictingsecond translation element 330 slidable within first translation element320, and fixable by a third locking screw or element 340.

A locking element 340 is provided to couple first and second translationelements 320, 330 with respect to each other, thereby fixing first andsecond translation elements 320, 330 from moving with respect to eachother and securing first and second connector elements 200A, 200B at adistance from each other. In an exemplary embodiment, locking element340 couples first and second translation elements 320, 330 in a dovetailconnection. A dovetail connection, as shown in the illustratedembodiments of FIGS. 5 and 6, provides a strong yet flexible geometry,arcing over a spinal column situated between first and second connectionmembers 200A, 200B. With a dovetail connection, translation, with littleor no rotation between translation elements 320, 330 is provided. In theembodiment illustrated in FIG. 2, first element 320 may operate tointernally receive second element 330, both elements 320, 330 slidableand rotatable with respect to each other thereby establishing a distancebetween first and second connector members 200A, 200B.

It is contemplated within the disclosure that device 100 can be utilizedas a cross-connector option for a spinal stabilization system, forexample interconnecting first and second spinal fixation rods within aposterior spinal fusion construct. Device 100, in addition to thepreviously disclosed connector options as well as the additionalconnector options described herein, are components of a modular systemwhich allows for screw tulip assembly to be attached to the screw headin-situ, following operations including, but not limited to:intervertebral operations, decortication, fusion bed preparation, etc.In reference now to FIGS. 7-13, additional embodiments of connectoroptions which may be utilized in a spinal stabilization system will nowbe described.

FIGS. 7A-7D illustrate an open offset connector 400A, in accordance withthe disclosure, which includes an engagement portion 410A for receivinga fixation element, a second locking set screw 420A with lockingassembly 430A, and a second locking set screw 440A for securing thereceived fixation element. Similar to connector members 200A, 200B, theengagement portion may be advantageously received in a preliminarysnap-fit or interference connection at engagement portion 410A. Secondlocking set screw 440A is provided to lock or clamp a received fixationelement within engagement portion 410A as screw 440A is rotated oradvanced into connector 400A. Open offset connector 400A may be offeredin both modular and preassembled configurations allowing for anextremely low profile iliac fixation point, which is particularlyadvantageous for surgical procedures performed on small staturepatients.

FIGS. 8A-8D illustrate a closed offset connector 400B, in accordancewith the disclosure, which includes engagement portion 410B, a firstlocking set screw 420A with locking assembly 430, and a second lockingset screw 440B for securing the received fixation element. Unlikeengagement portion 410A, engagement portion 410B is closed to fullyenclose a received spinal fixation element. In the embodiment disclosed,second locking set screw 420B is similar to second locking set screw420A, and locking assembly 430B is similar to locking assembly 430A,however it should be appreciated that different locking assembliesand/or set screws for establishing bone fixation, such as iliac fixationpoints, may be utilized in accordance with the disclosure. Closed offsetconnector 400B may also be offered in both modular and preassembledconfigurations allowing for extremely low profile fixation points.

Referring now to FIGS. 9A-9D and FIGS. 10A-10D illustrating embodimentsof tulip elements 500A, 500B which may be utilized as part of astabilization system, in accordance with the disclosure. Side-loadingtulip element 500A, includes a tulip 510A, locking set screw 520A, and alocking assembly 530A. Closed head tulip element 500B includes a tulip510B, locking set screw 520B, and a locking assembly 530B associatedwith locking screw 520B. Tulip elements 500A, 500B may be offered inboth modular and preassembled configuration and allow for a secure lowprofile fixation rod and bone screw or fastener connection point, whichis particularly useful for iliac fixation in a spinal fixationprocedure.

FIGS. 11A-11D illustrate a headed rod or implant 600 which may beutilized as part of a stabilization system, in accordance with thedisclosure. Implant 600 includes a connector element or rod 610, lockingset screw 620, and a locking assembly 630 associated with locking setscrew 620. Headed rod 600 may be offered in both modular andpreassembled configurations and allows for extremely low profilefixation points, for example in sacral fixation points, which is usefulfor small statute patients.

FIGS. 12A-12D illustrate a one level connector 700 which may be utilizedas part of a stabilization system, in accordance with the disclosure.One-level connector includes first and second locking set screws 710A,710B and first and second locking assemblies 720A, 720B associated withlocking set screws 710A, 710B. One level connector 700 may be offered inboth modular and preassembled configurations and allows for extremelylow profile fixation points, for example in sacral fixation points,which is useful for small statute patients.

FIGS. 13A and 13B illustrate a fixation plate or implant 800 which maybe utilized as part of a stabilization system, including for examplesacral fixation, in accordance with the disclosure. Fixation plate 800advantageously accommodates dual-point fixation by receiving a first rodor fixation element in a first aperture 810A, and a second rod orfixation element in a second aperture 810B, thereby allowing in-situattachment of any modular component as a part of a stabilization system.Provided on a first end of plate 800 is a protruding element 820, whichin some embodiments is threaded on an exterior surface in order to matewith another element and/or to improve the grip of a technicianattaching the plate as a component of a stabilization system. Providedon a surface of the plate opposite protruding element or knob 820 is apointed element or spike 830. The one-piece design, as shown in theillustrated embodiment of plate 800, is beneficial for bothmanufacturing and ease of attachment as a component of a stabilizationsystem. The dual-point fixation provided by plate 800 has shown to atleast 25% stronger than traditional constructs used in similar sacralfixation elements.

FIGS. 14A and 14B illustrate another embodiment of a connector 900 thatmay be utilized as part of a stabilization system. In particular, theconnector 900 may be a low profile, one-level connector that attachesdirectly to pedicle screws 950. The one-level connector 900 allows forcontrolled rotational movement and compression and/or elongation untilfinal tightening of the construct. The low profile design may beespecially useful for very small stature patients.

As shown in FIG. 14A, the one-level connector 900 includes a firstcoupling element 902 and a second coupling element 912. The first andsecond coupling elements 902, 912 are configured such that the firstcoupling element 902 can be rotated relative to the second couplingelement 912 or vice versa. The first and second coupling elements 902,912 are also configured such that the first and second coupling elements902, 912 are able to move toward one another and away from one another,thereby providing compression or distraction of adjacent vertebrae whenthe connector 900 is attached to the vertebrae.

As best seen in the exploded view in FIG. 14B, the assembly includes aone-level connector 900 and two bone fasteners 950 configured to beengaged by the connector 900. The bone fasteners 950 may each include ahead 952 and a threaded shaft 954 that extends from the head 952. Inthis embodiment, the head 952 is generally rounded and shaped to form aportion of a ball or at least a portion of a sphere. Thus, when receivedin the connector 900, the head 952 may allow for polyaxial movement ofthe fastener 950. It is contemplated that the bone fastener 950 may beconfigured to move polyaxially, monoaxially, or uni-planar with respectto the connector 900. The head 952 may be substantially smooth,partially or fully threaded, or otherwise textured. The threaded shaft954 may have a blunt tip, a sharp point, or the like and may be taperedalong its length. The threaded shaft 954 is configured to engage bone,and may be particular suitable for being secured in the pedicle of avertebra. Threaded cutting flutes may be provided for self-tapping. Thescrew head 952 may include any suitable driving recess, e.g., ahexalobular recess, for screw insertion.

With further emphasis on FIG. 14A, the connector 900 includes a firstcoupling element 902 configured to receive the head 952 of the firstbone fastener 950. The first coupling element 902 includes a bodyportion 904 and an opening 906 extending longitudinally through the bodyportion 904. The locking assembly 930A including locking set screw 936Amay be sized and dimensioned to be received in the opening 906 in thebody portion 904 of the first coupling element 902. The head 952 of thefastener 950 may be sized and dimensioned to be received within aportion of the locking assembly 930A as described in more detail herein.The first coupling element 902 may further include a connector elementor rod portion 910 extending transversely from the body portion 904. Therod portion 910 may include an elongate cylindrical portion or may havea cross-section that is substantially square, round, elliptical, or ofany other suitable shape. In a preferred embodiment, the rod portion 910is substantially cylindrical in shape to allow for controlled rotationof the first coupling element 902 relative to the second couplingelement 912. The first coupling element 902 may be similar to implant600 described elsewhere herein.

The locking assembly 930A may be similar to the other locking assembliesdescribed herein. The locking assembly 930A includes a clamp portion932A, a ring portion 934A, and a locking set screw 936A. The locking setscrew 936A includes a base portion 940A and an engagement portion havingany suitable driving recess, e.g., a hexalobular recess, for locking andunlocking of the set screw 936A. The locking set screw 936A may includethreaded or non-threaded locking features designed to allow for a lockedposition and an unlocked position, for example, when the set screw 936Ais rotated. The base portion 940A is configured to be received in thering portion 934A and optionally into contact with a top face of theclamp portion 932A when the locking set screw 936A is locked. The ringportion 934A may be configured to surround the locking set screw 936Aand an upper portion of the clamp portion 932A. When the locking setscrew 936A is locked, the head 952 of the bone fastener 950 is locked inthe first coupling element 902 and is locked into position relative tothe first coupling element 902.

The clamp portion 932A of the locking assembly 930A is configured to atleast partially surround the head 952 of the fastener 950. The head 952may be received in the clamp portion 932A, for example, with aprovisional interference fit. When unlocked, the clamp portion 932 maybe configured to move or articulate to allow, for example, polyaxialmovement of the bone fastener 950. The clamp portion 932A may have anouter surface, for example, with a plurality or protrusions andrecesses, a threaded portion, or other texture. The clamp portion 932Amay also include at least one slit 938A extending therethrough to allowthe clamp portion 932A to be compressed around the head 952 of thefastener 950 when the locking assembly 930A is locked. The slit 938A mayextend from a top portion to a bottom portion of the clamp portion 932Aand may extend completely or partially therethrough. The slit 938A maybe linear or non-linear in shape. As shown in FIG. 14A, the slit 938 mayhave an angled portion, a perpendicular portion extending substantiallytransverse to the longitudinal axis, and a longitudinal portionextending along the longitudinal axis of the body portion 904 of thefirst coupling element 902. The configuration and number of slits 938Amay be selected to obtain the desired amount of compression on the head952 of the fastener 950.

When the locking assembly 930A is in its locked position, the lockingset screw 936A can be advanced through the body portion 904 to engagethe ring portion 934A and/or the clamp portion 932A, thereby applyingdownward force onto clamp portion 932A and securing the bone fastener950 to the first coupling element 902. In one embodiment, the lockingset screw 936A forces the ring portion 934A downward and into contactwith the clamp portion 932A causing the locking assembly 930A to movedownward in the first coupling element 902 and secure the fastener 950in its final implanted position.

The one-level connector 900 includes a second coupling element 912configured to receive the head 952 of the second bone fastener 950. Thesecond coupling element 912 may include a body portion 914 having anopening 916 extending longitudinally therethrough. The locking assembly930B may be sized and dimensioned to be received in the opening 916 inthe body portion 914 of the second coupling element 912. The lockingassembly 930B includes clamp portion 932B having slit 938B, ring portion934B, and locking set screw 936B including base portion 940B. Thecomponents and functionality of locking assembly 930B are substantiallythe same as for locking assembly 930A and are therefore not repeated indetail for brevity, but would apply equally for locking assembly 930B.

The second coupling element 912 includes an extension portion 918defining a recess 920 therein. The extension portion 918 may extendsubstantially transverse from the coupling element 912. The recess 920may be in the form of a blind hole. The recess 920 may extend throughthe length of the extension portion 918. The recess 920 may terminatebefore the body portion 914 or optionally may enter the body portion914. The recess 920 may be dimensioned and configured to receive the rodportion 910 of the first coupling element 902. Accordingly, the recess920, extending a distance into the extension portion 918, may have anelongate cylindrical portion or may have a cross-section that issubstantially square, round, elliptical, or any other shape thatsubstantially corresponds to the outer dimensions of the rod portion 910of the first coupling element 902. Although depicted with the firstcoupling element 902 having the rod portion 910 and the second couplingelement 912 having the extension portion 918 with the recess 920, whichreceives the rod portion 910, it will be appreciated that thesecomponents may be reversed such that the first coupling element 902 isprovided with a recess and the second coupling element 912 is providedwith a rod portion to be received within the recess or any othersuitable configuration.

The rod portion 910 is configured to be received within the recess 920in the extension portion 918 such that controlled rotational movementand compression and/or elongation may be obtained by the user. Inparticular, the body portion 904 of the first coupling element 902 maybe rotated relative to the body portion 914 of the second couplingelement 912. By rotating the first and second coupling elements 902, 912with respect to one another, the first and second bone fasteners 950 maybe offset to one another at a desired angle. If rotation is not desired,the first and second bone fasteners 950 may be aligned with one another.

The body portion 904 of the first coupling element 902 may also be movedin a general direction towards or away from the body portion 914 of thesecond coupling element 912, thereby shortening or lengthening therelative length of the overall connector 900 in order to apply acompressive or distractive force to the vertebrae. When the overalllength of the connector 900 is shortened to its smallest length, the endof the rod portion 910 may abut the innermost portion of the recess 920and/or an outermost portion of the extension 918 may abut the outside ofthe body portion 904. When the overall length of the connector 900 isincreased, a gap forms between the end of the rod portion 910 and theinnermost portion of the recess 920 and/or the outermost portion of theextension 918 and the outside of the body portion 904. The gap willincrease as the length of the connector 900 is increased until a maximumlength is obtained.

Once the desired orientation including rotation and distance between thefirst and second coupling elements 902, 912 is achieved, the relativeposition can be locked by locking member or locking set screw 946positioned in extension portion 918 of the second coupling element 912.The locking set screw 946 may also include any suitable driving recess,e.g., a hexalobular recess, for locking and unlocking of the set screw946. The locking set screw 946, similar to locking set screws 936A,936B, may include threaded or non-threaded locking features designed toallow for a locked position and an unlocked position, for example, whenthe set screw 946 is rotated. The locking set screw 946 may beconfigured to apply a force on the rod portion 910 of the first couplingelement 902, for example, when the locking set screw 946 is moveddownward and into contact with an outer surface of the rod portion 910of the first coupling element 902. The rod portion 910 may also beconfigured with an indentation or groove (not shown), for example, toreceive the bottom surface of the locking set screw 946 when locked.

According to a method, the connector 900 may be used to perform aone-level spinal fusion. For example, the posterior aspects of the spinemay be exposed or accessed via a minimally invasive surgical (MIS)approach. A first bone fastener 950 may be inserted into the pedicle ofa first vertebra and a second bone fastener 950 may be inserted into thepedicle of a second, adjacent vertebra. The bone fasteners 950 arepreferably inserted such that the heads 952 remain proud above the bone.After the bone fasteners 950 are secured, the connector 900 may beattached to the heads 952 of the respective bone fasteners 950. Inparticular, the heads 952 of the bone fasteners 950 may be received inthe respective first and second coupling elements 902, 912. The firstand second coupling elements 902, 912 may provisionally receive thefasteners 950, for example, with an interference fit.

The relative position of the connector 900 and fasteners 950 may bemodified or changed until the desired orientation is achieved. Inparticular, the length of the connector 900 may be expanded orcontracted by translating the rod portion 910 in the recess 920 of theextension portion 918. In addition, the first coupling element 902 maybe rotated relative to the second coupling element 912 such that thebone fasteners 950 are angled with respect to one another. Therotational and translational movement of the connector 900 may occursimultaneously or sequentially in any suitable order. It is alsocontemplated that the fasteners 950 are polyaxially rotated andpositioned with respect to the connector 900.

Once the final positioning has been obtained, the locking set screws936A, 936B, and 946 may be tightened to achieve the final construct. Thelocking set screws 936A, 936B, and 946 may be tightened sequentially, inany suitable order, or simultaneously. Although not depicted, thelocking set screw 936A, 936B, and 946 may also include a back-outprevention feature. The locking set screws 936A, 936B secure thefasteners 950 in the respective first and second coupling elements 902,912, and the locking set screw 946 secures the rod portion 910 of thefirst coupling element 902 within recess 920 in the extension portion918 of the second coupling element 912, thereby locking the length androtational position of the connector 900. Thus, the low profileconnector 900 allows for controlled rotational relationships andcompression or elongation after final tightening of the construct.

Turning now to FIGS. 15-18, alternative components for a modular systemwhich allow for attachment to one or more bone fasteners, such aspedicle screws 950 and/or one or more elongate fixation elements, suchas elongate rods 960 are shown. The modular components may includeheaded rods, open offset connectors, closed offset connectors, one-levelconnectors, and the like. The features from one embodiment may be usedin any other embodiment. The modular components may be suitable, forexample, for intervertebral operations, decortication, fusion bedpreparation, etc. The components may be connected to new or existingconstructs.

FIGS. 15A-15C illustrate a headed rod or implant 1000 which may beutilized as part of a stabilization system. Implant 1000 includes aconnector or coupling element 1002 with an integral rod 1010. Headed rod1000 may be offered in both modular and preassembled configurations andallows for extremely low profile fixation points, for example in sacralfixation points, which is useful for small statute patients.

The headed rod connector or implant 1000 may be a low profile connectorthat attaches directly to a bone fastener, such as a pedicle screw 950.As shown in FIG. 15B, the implant 1000 includes a coupling element 1002configured to receive the head 952 of the pedicle screw 950. Whenreceived in the connector 1000, the head 952 may allow for polyaxialmovement of the fastener 950 relative to the coupling element 1002. Itis also contemplated that the bone fastener 950 may be configured tomove polyaxially, monoaxially, or uni-planar with respect to theconnector 1000.

The coupling element 1002 includes a body portion 1004 and an opening1006 extending longitudinally through the body portion 1004. A lockingassembly 1030 or a portion thereof may be sized and dimensioned to bereceived in the opening 1006 in the body portion 1004 of the couplingelement 1002. The head 952 of the fastener 950 may be sized anddimensioned to be received within a portion of the locking assembly 1030as described in more detail herein.

The coupling element 1002 may further include a connector element or rodportion 1010 extending transversely from the body portion 1004. The rodportion 1010 may be substantially integral with the coupling element1002, for example, extending from an upper portion or central portion ofthe coupling element 1002. The rod portion 1010 may have a lengthgreater than the width or outer diameter of the coupling element 1002.The rod portion 1010 may terminate at a free end. For example, the rodportion 1010 may terminate a given distance away from the couplingelement 1002. The free end of the rod portion 1010 may be blunt,pointed, or otherwise configured. The rod portion 1010 may include anelongate cylindrical portion or may have a cross-section that issubstantially square, round, elliptical, or of any other suitable shape.The rod portion 1010 may be sized and dimensioned to be received in atraditional tulip element (not shown). In a preferred embodiment, therod portion 1010 is substantially cylindrical in shape to couple to atraditional tulip assembly, for example, comprising a second pediclescrew.

The locking assembly 1030 may include similar features to the otherlocking assemblies described herein. As best seen in the exploded viewin FIG. 15C, the locking assembly 1030 includes a clamp portion 1032, aring portion 1034, and a locking set screw 1036. The locking set screw1036 includes a base portion 1040 and an engagement portion having anysuitable driving recess, e.g., a hexalobular recess, for locking andunlocking of the set screw 1036. The locking set screw 1036 may includethreaded or non-threaded locking features designed to allow for a lockedposition and an unlocked position, for example, when the set screw 1036is rotated. The base portion 1040 is configured to contact a top face ofthe clamp portion 1032 when the locking set screw 1036 is locked. Thering portion 1034, for example, in the form a snap ring, may beconfigured to surround the base of the clamp portion 1032. The ringportion 1034 may be configured to substantially seat in the bottom ofthe coupling element 1002. The ring portion 1034 may form a complete orpartial ring, for example, with a gap separating first and second endsof the ring portion 1034. When the locking set screw 1036 is locked, thering portion 1034 surrounds the lower portion of the clamp portion 1032and is seated in the base of the coupling element 1002, thereby lockingthe head 952 of the bone fastener 950 in the coupling element 1002.

The clamp portion 1032 of the locking assembly 1030 is configured to atleast partially surround the head 952 of the fastener 950. The head 952may be received in the clamp portion 1032, for example, with aprovisional interference fit. When unlocked, the clamp portion 1032 maybe configured to move or articulate to allow, for example, polyaxialmovement of the bone fastener 950. The clamp portion 1032 may have anouter surface, for example, with a plurality or protrusions andrecesses, a threaded portion, or other texture. The clamp portion 1032may also include at least one slit 1038 extending therethrough to allowthe clamp portion 1032 to be compressed around the head 952 of thefastener 950, for example, when the snap ring 1034 tightens around thebase of the clamp portion 1032. The slit 1038 may extend from a topportion to a bottom portion of the clamp portion 1032 or along a lengththereof and may extend completely or partially therethrough. The slit1038 may be linear or non-linear in shape. The configuration and numberof slits 1038 may be selected to obtain the desired amount ofcompression on the head 952 of the fastener 950 when the ring portion1034 compresses the clamp portion 1032.

According to a method, the connector 1000 may be used to extend anexisting fusion construct. For example, the posterior aspects of thespine may be exposed or accessed via a minimally invasive surgical (MIS)approach. The coupling element 1002 may be positioned onto an existingbone fastener 950, which was previously secured into the pedicle of afirst vertebra. A tulip including a second bone fastener 950 may beinserted into the pedicle of a second, adjacent vertebra and the tulipmay be attached to the rod portion 1010 of the connector 1000. Once thefinal positioning has been obtained, the locking set screw 1036 may betightened to achieve the final construct.

FIGS. 16A-16B illustrate an open offset connector or implant 1100 whichmay be utilized as part of a stabilization system. The coupling element1002 and locking assembly 1030 are substantially the same as thatdisclosed for the connector 1000 in FIGS. 15A-15C. Instead of theintegral rod, implant 1100 includes a connector or coupling element 1002with an integral rod receiving channel or engagement portion 1050A. Therod receiving channel or engagement portion 1050A is configured toreceive a fixation element, such as an elongate rod 960. Open offsetconnector 1000 may be offered in both modular and preassembledconfigurations allowing for an extremely low profile iliac fixationpoint, which is particularly advantageous for surgical proceduresperformed on small stature patients.

Implant 1100 includes engagement portion 1050A for receiving a fixationelement, such as an elongate rod 960, and a second locking set screw1060 for securing the received fixation element therein. The engagementportion 1050A may include a c-shaped channel or opening configured tomimic at least a portion of the outer configuration of the elongate rod960. The second set screw 1060 may be received in an opening of theimplant 1100 positioned above and in fluid communication with thec-shaped channel. The base of the second set screw 1060 may include oneor more tapered or angled portions such that when the set screw 1060 islowered into the c-shaped channel, the base of the second set screw 1060contacts an upper or side surface of the elongate rod 960, therebysecuring the rod 960 in the implant 1100. Similar to connector member400A shown in FIGS. 7A-7B, the elongate rod 960 may be advantageouslyreceived in a preliminary snap-fit or interference connection atengagement portion 1050A. Second locking set screw 1060 may be providedto lock or clamp the elongate rod 960 within the engagement portion1050A as screw 1060 is rotated or advanced into connector 1100.

FIGS. 17A-17C illustrate a closed offset connector 1200 which may beutilized as part of a stabilization system. The coupling element 1002and locking assembly 1030 are substantially the same as that disclosedfor the connector 1000 in FIGS. 15A-15C. Instead of the integral rod,implant 1200 includes a connector or coupling element 1002 with anintegral closed rod receiving opening or engagement portion 1050B. Theclosed rod receiving opening or engagement portion 1050B is configuredto receive a fixation element, such as an elongate rod 960.

Unlike engagement portion 1050A, engagement portion 1050B is closed tofully enclose a received spinal fixation element, such as an elongaterod 960. Thus, the engagement portion 1050A may completely encircle theelongate rod 960. The closed opening in the engagement portion 1050A maybe substantially cylindrical, oval, or otherwise complementary to theshape of the rod 960. The second locking set screw 1060 advances throughan opening in the top portion of the implant 1200, which is in fluidcommunication with the closed opening, to engage an upper surface of therod 960, thereby securing the rod 960 therein. The second locking setscrew 1060 may be similar to locking set screw 1036, however, it shouldbe appreciated that different locking assemblies and/or set screws forestablishing bone fixation, such as iliac fixation points, may beutilized. Closed offset connector 1200 may also be offered in bothmodular and preassembled configurations allowing for extremely lowprofile fixation points.

FIGS. 18A-18B illustrate a one level connector 1300 which may beutilized as part of a stabilization system. Instead of the integral rod,implant 1300 includes a first connector or coupling element 1002 with anintegral, second connector or coupling element 1002. The couplingelements 1002 and locking assemblies 1030 are substantially the same asthat disclosed for the connector 1000 in FIGS. 15A-15C. One-levelconnector 1300 includes first and second coupling elements 1002 andfirst and second locking assemblies 1030 associated with the first andsecond coupling elements 1002. The first and second coupling elements1002 may be separated a distance from one another, for example, by a rodportion, interconnecting the two adjacent coupling elements 1002. Onelevel connector 1300 may be offered in both modular and preassembledconfigurations and allows for extremely low profile fixation points, forexample in sacral fixation points, which is useful for small statutepatients.

All references cited herein are expressly incorporated by reference intheir entirety. There are many different features to the presentinvention and it is contemplated that these features may be usedtogether or separately. Thus, the features of one embodiment may be usedin another embodiment. Unless mention was made above to the contrary, itshould be noted that all of the accompanying drawings are not to scale.Thus, the invention should not be limited to any particular combinationof features or to a particular application of the invention. Further, itshould be understood that variations and modifications within the spiritand scope of the invention might occur to those skilled in the art towhich the invention pertains. Accordingly, all expedient modificationsreadily attainable by one versed in the art from the disclosure setforth herein that are within the scope and spirit of the presentinvention are to be included as further embodiments of the presentinvention.

What is claimed is:
 1. A coupling device comprising: a bone fastener having a head portion; a coupling element having a body portion for receiving the bone fastener and an extension portion extending transversely from the body portion; and a locking assembly received in the coupling element, the locking assembly including a locking member, a clamp portion, and a ring portion, wherein the locking member is configured to contact an upper portion of the clamp portion and the ring portion is configured to at least partially surround a lower portion of the clamp portion, wherein the clamp portion is configured to engage a portion of the head portion of the bone fastener, and wherein the ring portion is configured to engage a portion of the head portion of the bone fastener, wherein, when unlocked, the bone fastener is moveable with respect to the clamp portion to allow for polyaxial movement of bone fastener relative to the coupling element, and when locked, the bone fastener is fixed relative to the coupling element, wherein the clamp portion includes at least one slit extending therethrough to allow the clamp portion to be compressed around the head portion of the bone fastener when the locking assembly is locked, and wherein the at least one slit extends through the lower portion of the clamp portion and toward the upper portion of the clamp portion without extending through an upper surface of the clamp portion, and wherein an upper portion of the ring portion comprises an annular collar extending radially outward.
 2. The device of claim 1, wherein the extension portion is in the form of an elongate rod terminating at a free end.
 3. The device of claim 1, wherein the extension portion is in the form of an engagement portion having an open rod receiving channel configured to receive an elongate rod.
 4. The device of claim 3, wherein the open rod receiving channel is a c-shaped channel configured to receive the elongate rod, and the elongate rod is secured in the c-shaped channel by a second locking member.
 5. The device of claim 1, wherein the extension portion is in the form of an engagement portion having a closed rod receiving channel configured to receive an elongate rod.
 6. The device of claim 5, wherein the closed rod receiving channel is a substantially cylindrical shaped opening configured to receive the elongate rod, and the elongate rod is secured in the cylindrical shaped opening by a second locking member.
 7. The device of claim 1, further comprising a second coupling element having a second body portion and a second locking assembly connected to the extension portion of the coupling element.
 8. The device of claim 7, wherein the second locking assembly includes a second locking member, a second clamp portion, and a second ring portion, wherein the second locking member is configured to contact an upper portion of the second clamp portion and the second ring portion is configured to at least partially surround a lower portion of the second clamp portion.
 9. The device of claim 1, wherein the locking member is in the form of a set screw configured to apply a downward force on the clamp portion and cause the ring portion to clamp around the clamp portion, thereby locking the bone fastener therein.
 10. The assembly of claim 1, wherein the at least one slit is non-linear in shape.
 11. A coupling assembly comprising: a first bone fastener having a head and a shaft extending therefrom, the shaft configured to engage a first vertebra; a first coupling element having a first body portion housing a first locking assembly and an extension portion extending transversely from the first body portion, the first locking assembly comprising a first rotatable locking member, a first clamp portion, and a first ring portion configured to at least partially surround only a lower portion of the first clamp portion, and the head of the first bone fastener is received in the first clamp portion; and wherein, when unlocked, the first bone fastener is moveable in the first clamp portion to allow for polyaxial movement of the first bone fastener relative to the first clamp portion, and when locked, the position of the first bone fastener is fixed relative to the first coupling element, wherein the first clamp portion includes at least one slit extending therethrough to allow the first clamp portion to be compressed around the head of the first bone fastener when the first locking assembly is locked, and wherein the at least one slit extends through the lower portion of the first clamp portion and toward an upper portion of the first clamp portion without extending through an upper surface of the first clamp portion, and wherein an upper portion of the first ring portion comprises an annular collar extending radially outward.
 12. The assembly of claim 11, wherein the extension portion is in the form of an elongate rod terminating at a free end.
 13. The assembly of claim 11, wherein the extension portion is in the form of an engagement portion having an open rod receiving channel configured to receive an elongate rod.
 14. The assembly of claim 13, wherein the open rod receiving channel is a c-shaped channel configured to receive the elongate rod, and the elongate rod is secured in the c-shaped channel by a second locking member.
 15. The assembly of claim 11, wherein the extension portion is in the form of an engagement portion having a closed rod receiving channel configured to receive an elongate rod.
 16. The assembly of claim 15, wherein the closed rod receiving channel is a substantially cylindrical shaped opening configured to receive the elongate rod, and the elongate rod is secured in the cylindrical shaped opening by a second locking member.
 17. The assembly of claim 11, further comprising a second coupling element having a second body portion and a second locking assembly connected to the extension portion of the first coupling element.
 18. The assembly of claim 17, wherein the second locking assembly includes a second locking member, a second clamp portion, and a second ring portion, wherein the second locking member is configured to contact an upper portion of the second clamp portion and the second ring portion is configured to at least partially surround a lower portion of the second clamp portion.
 19. The assembly of claim 11, wherein the first locking member is in the form of a set screw configured to apply a downward force on the first clamp portion and cause the first ring portion to clamp around the first clamp portion, thereby locking the first bone fastener therein. 